Which statement best describes the variables in a controlled experiment?

control is constant for given set of readings.

set indep var

observe dep var

The independent variable is changed to see its effect on the dependent variable while all other conditions are unchanged is the correct answer.

Explanation:

A variable are the things that change in an experiment, such as conditions, factors, or traits that can exist. There are usually three types of them: independent, dependent, and controlled.

The independent is changed by the scientist; the dependent ones are those that receive specific attention from the scientist, who wants to see how they change. The controlled ones are those quantities that the scientist wants to remain constant.

a.) is the correct answer.

explanation:

answer: the rock sample is a sedimentary rock.

explanation:

it is given that:

mass of rock sample, m = 2.7 g

volume of rock sample,

so, density of rock sample will be

since, the density of rock sample is . hence, the rock sample is a sedimentary rock, whose densities varies between .